Atlas of plant and animal histology

Fixatives are solutions of substances for preserving the morphological features of tissues similar to the alive features. They allow the processing of biological samples through histological techniques, minimizing the degradation of tissue structures. There are many fixative solutions that are chosen regarding the sample and the feature of the tissue to be studied.

PLP (periodate, lysine, paraformaldehyde) fixative solution is recommended for immunostaining, since it preserves antigens. Carbohydrates are fixed, since the fixative contains peryodate that oxidizes carnohydrates to form aldehydes and lysine forms bridges between them, thus cross-linking the molecules. Paraformaldehyde (formaldehyde when solved) is used at low concentration to estabilize the tissue. PLP is also a good fixative for electron microscopy, since it preserve membranes, so that the tissue can be processed for electron microscopy.

Procedure

Solution A: add sodium phosphate dibasic 0.1 M to a solution containing lysine-HCl 0.2 M until the pH is 7.4. The resulting solution is diluted in buffer phosphate 0.1 M, pH 7.4 to get a final lysine-HCl concentration of 0.1 M.

Solution B: 8 % of paraformaldehyde in destilled H₂O .

Fixative solution: mix 3 parts of solution A with 1 part of solution B, and add solid sodium metaperiodate to get a final concentration of 0.01 M of sodium metaperiodate.

Solutions

Lysine-HCl: 0.2 M of Lysine-HCl in distilled water H₂O

Sodium phosphate dibasic: 0.1 M of sodium phosphate dibasic in distilled H₂O.

Sodium buffer phosphate: 0.1 M od sodium buffer phosphate in distilled H₂O.

Paraformaldehyde: 8 % of paraformaldehyde in distilled H₂O.

Notes

It is important to add the products and solutions in the order described above.

Products

Lysine-HCl

Dibasic sodium phosphate (Na₂HPO₄)

Sodium phosphate buffer

Paraformaldehyde

Sodium metaperiodate (NaI0₄)

Distilled H₂O

Labware

Test tube

Balance

pH meter

Magnetic stirrer/heat plate

Flasks

Bottles

• Bibliography ↷

  • Brenes F, Harris S, Paz MO, Petrovic LM, Scheuer PJ. 1986. PLP fixation for combined routine histology and immunocytochemistry of liver biopsies. Journal of clinical pathology 39: 459-563.